The panleonist
theory proposes that a highly advanced civilization existed on the
Earth during during the precessional age of Leo (c. 10900-8700 BC), but
was destroyed by a cataclysm circa 10500 BC and hence became a ‘lost
civilisation’. The theory proposes that the lost civilisation encoded
the date 10500 BC into their monuments.

The panleonist theory is best known from the writings of Robert Bauval,
Adrian Gilbert and Graham Hancock. But it has its roots in an
assortment of different writings. Firstly, in Plato’s story of
Atlantis, which recalled the destruction of an advanced civilization
nine thousand years before the time of Solon, i.e. c. 9600 BC.
Secondly, in the prophecies of certain mystics, such as Edgar Cayce.
And thirdly, in the writings of Zecharia Sitchin, who dated the
beginning of history to the Great Flood in 11000 BC, at the beginning
of the age of Leo.

The
Orion Theory

In ‘The Orion Mystery’ (1994), Robert Bauval and Adrian Gilbert made a
very interesting discovery, namely that the three main pyramids at Giza
(of Khufu, Khafre and Menkaure) formed a pattern on the ground
virtually identical to that of the three belt stars of the Orion
constellation. This was a perfectly plausible hypothesis. However,
Bauval and Gilbert then entered controversial territory. Using computer
software, they wound back the Earth’s skies to ancient times, and
witnessed a ‘locking-in’ of the mirror image between the pyramids and
the stars at the same time as Orion reached a turning point at the
bottom of its precessional shift up and down the meridian. This
conjunction, they claimed, was exact, and it occurred precisely at the
date 10450 BC.

Robert
Bauval teamed up with Graham
Hancock, and took the 10500 BC theory further, claiming corroborative
evidence in the form of the Sphinx at Giza (see below).

Sphinix looking at it's Constellation of Leo in 10500 B.C.

Graham Hancock argued that the
date 10500 BC was encoded also at the ancient Cambodian site of Angkor
Wat (the temples, he alleged, were in the image of the constellation
Draco at exactly 10500 BC).